The present invention relates to electronic price label (EPL) systems, and more specifically to a method of minimizing power consumption within an EPL.
EPL systems typically include a plurality of EPLs for each merchandise item in a store. EPLs include displays which display the price of corresponding merchandise items on store shelves and are typically attached to a rail along the leading edge of the shelves. EPL systems typically obtain their prices from the POS server's PLU file. A store may contain thousands of EPLs to display the prices of the merchandise items. The EPLs are coupled to a central server from where information about the EPLs is typically maintained in an EPL data file. The EPL data file contains EPL identification information, and EPL merchandise item information.
EPLs are typically powered by batteries. The current expected life of an EPL battery is about 5-7 years. Receiving circuitry draws most of the power, even though operation of the receiving circuitry is only required during transmission of messages from the central server.
Various methods of saving EPL battery life are disclosed in European Patents Nos. WO 9411834 and WO 9411833. A monitoring module automatically senses a power drop from the main source of power (a solar panel) to initiate a power saving mode of operation. After an operating time t, the monitoring module removes power from high power components for a time n*t.
However, inclusion of a separate monitoring module adds cost to an EPL. The cost is significant to an installation involving thousands of EPLS. Also, requiring that all EPLs sleep after an interval t for a period n*t is inconsistent with the system utilization. An EPL system can track and anticipate when communications (e.g., price changes) need to occur. The system's ability to anticipate allows it to improve throughput because the EPLs are ready when needed. Additionally, if anticipation is done correctly, EPLs could be made to sleep longer, thus prolonging their battery lives. For example, if a retailer only makes price changes at night between midnight and six o'clock a.m., then the EPLs can actually sleep for eighteen hours per day.
Therefore, it would be desirable to provide a method of minimizing power consumption within an EPL that minimizes the cost of the EPL.